Revert "PM: ACPI: reboot: Use S5 for reboot"

This reverts commit d60cd063.

This patch causes a panic when rebooting my Dell Poweredge r440.  I do
not have the full panic log as it's lost at that stage of the reboot and
I do not have a serial console.  Reverting this patch makes my system
able to reboot again.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

kernel/reboot.c

@@ -244,8 +244,6 @@ void migrate_to_reboot_cpu(void)
 void kernel_restart(char *cmd)
 {
 	kernel_restart_prepare(cmd);
-	if (pm_power_off_prepare)
-		pm_power_off_prepare();
 	migrate_to_reboot_cpu();
 	syscore_shutdown();
 	if (!cmd)